def chisl(s):
     k=''
    if s == 'zero':k='0'
    elif s == 'one':k='1'
    elif s == 'two':k='2'
    elif s == 'three':k='3'
    elif s == 'four':k='4'
    elif s == 'five':k='5'
    elif s == 'six':k='6'
    elif s == 'seven':k='7'
    elif s == 'eight':k='8'
    elif s == 'nine':k='9'
    return k

prost = [101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997]
s1, s2, s3 = input(),split()
a1, a2 = 0,0
num = int(chisl(s1)+chisl(s2)+chisl(s3))
for x in range (len(prost))
    if prost[x]>num:
        a2 = x
        a1 = x-1
        break
   
if abs (prost[a1] - num) > prost[a2] - num:
     print(prost[a2])
elif abs(prost[a1] - num) <= prost[a2] - num:
     print(prost[a1])
     